Medical Biotechnology, VTT Technical Research Centre of Finland, Turku, Finland.
Cancer Res. 2011 Mar 1;71(5):1956-67. doi: 10.1158/0008-5472.CAN-10-2421. Epub 2011 Feb 22.
Androgen receptor (AR) is expressed in all stages of prostate cancer progression, including in castration-resistant tumors. Eliminating AR function continues to represent a focus of therapeutic investigation, but AR regulatory mechanisms remain poorly understood. To systematically characterize mechanisms involving microRNAs (miRNAs), we conducted a gain-of function screen of 1129 miRNA molecules in a panel of human prostate cancer cell lines and quantified changes in AR protein content using protein lysate microarrays. In this way, we defined 71 unique miRNAs that influenced the level of AR in human prostate cancer cells. RNA sequencing data revealed that the 3'UTR of AR (and other genes) is much longer than currently used in miRNA target prediction programs. Our own analyses predicted that most of the miRNA regulation of AR would target an extended 6 kb 3'UTR. 3'UTR-binding assays validated 13 miRNAs that are able to regulate this long AR 3'UTR (miR-135b, miR-185, miR-297, miR-299-3p, miR-34a, miR-34c, miR-371-3p, miR-421, miR-449a, miR-449b, miR-634, miR-654-5p, and miR-9). Fifteen AR downregulating miRNAs decreased androgen-induced proliferation of prostate cancer cells. In particular, analysis of clinical prostate cancers confirmed a negative correlation of miR-34a and miR-34c expression with AR levels. Our findings establish that miRNAs interacting with the long 3'UTR of the AR gene are important regulators of AR protein levels, with implications for developing new therapeutic strategies to inhibit AR function and androgen-dependent cell growth.
雄激素受体（AR）在前列腺癌进展的所有阶段都有表达，包括在去势抵抗性肿瘤中。消除 AR 功能仍然是治疗研究的重点，但 AR 调节机制仍知之甚少。为了系统地描述涉及 microRNAs（miRNAs）的机制，我们在一系列人前列腺癌细胞系中进行了 1129 种 miRNA 分子的功能获得筛选，并使用蛋白质裂解物微阵列定量测定 AR 蛋白含量的变化。通过这种方式，我们定义了 71 种独特的 miRNA，它们影响人前列腺癌细胞中 AR 的水平。RNA 测序数据显示，AR（和其他基因）的 3'UTR 比目前 miRNA 靶标预测程序中使用的要长得多。我们自己的分析预测，大多数 miRNA 对 AR 的调控将靶向一个扩展的 6 kb 3'UTR。3'UTR 结合测定验证了 13 种能够调节这个长 AR 3'UTR 的 miRNA（miR-135b、miR-185、miR-297、miR-299-3p、miR-34a、miR-34c、miR-371-3p、miR-421、miR-449a、miR-449b、miR-634、miR-654-5p 和 miR-9）。15 种下调 AR 的 miRNA 减少了前列腺癌细胞对雄激素诱导的增殖。特别是，对临床前列腺癌的分析证实，miR-34a 和 miR-34c 的表达与 AR 水平呈负相关。我们的研究结果表明，与 AR 基因的长 3'UTR 相互作用的 miRNAs 是 AR 蛋白水平的重要调节因子，这对开发抑制 AR 功能和雄激素依赖性细胞生长的新治疗策略具有重要意义。
